1. Field of the Invention
This invention relates to the machine tool art, and in particular to cutting tool bit holders for machine tools.
2. Description of the Prior Art
The present invention is concerned with cutting tool bit holders for machine tools and particularly pipe end preparation tools used to machine pipe ends to obtain specified configurations and dimensions of such pipe ends in preparation for welding operations.
A representative example of a tool of this kind is disclosed in U.S. Pat. No. 3,051,059 granted in 1962 to G. F. Davey. The tool shown in this patent provides a particularly good illustration of how prior art tooling concerned with pipe end milling and turning typically utilized rather massive and specially formed cutter bits which, according to usual practice, were ground and sharpened to be operational in a single carefully set position on the tool bit carrier which carried the bits in a circular cutting orbit about the tool axis.
The bits made in accordance with prior art techniques usually tend to be specialized, expensive, and rather massive when large workpieces are involved. Moreover, it is generally not considered to be economical to dispose of the bits when they become dulled from continued usage so they are usually resharpened or reworked by skilled toolmakers and returned to service by skilled operators who must again locate the bits in their precise cutting position on the machine tool head in preparation for continued operations.
The tool bits according to the prior usually are not reversible because of various technical considerations that are well-known to tool makers, including the fact that the various rake and cant angles ground into the tools are usually unique for each cutting direction and tool bit orientation.
It has been recognized by the inventor of the present invention that it would be highly desirable to provide a tool bit holder for a pipe end preparation tool that would enable the use of a less costly and simpler standardized tool bit that could be reversibly used, replaced by non-skilled labor, sufficiently inexpensive to be disposable after a relatively short service life, and which could support the tool bit in various positions on the tool head without elaborate set-up time or critical locating requirements. Such a holder, in addition, would be able to support the cutter tool bit in a variety of positions relative to the tool head and possess sufficient rigidity and strength so as to prevent vibration and chatter of the tool during cutting operations.
The present invention is intended and has for its objective the achievement of the above-mentioned characteristics for a tool holder.